This research involves testing the developmental potential of amphibian nuclei by transplantation into oocytes to determine whether nuclei remain genetically equivalent throughout cell differentiation. If the oocytes develop into normal frogs, this result would demonstrate that nuclei remain developmentally totipotent; if, however, normal development does not occur, this result would indicate that nuclei undergo stable genetic restrictions during cell differentiation. Oocytes are used instead of mature eggs, so that transplanted nuclei can be incubated and conditioned over extended periods of time.